Ariston 65104333 Secondary Heat Exchanger

The Ariston 65104333 is a secondary heat exchanger, a plate-type component used in Ariston gas boilers to transfer heat from the primary heating circuit into the domestic hot water supply. It sits on the DHW side of the appliance, so its condition directly affects hot water temperature stability and flow rate. This part is listed as a heat exchanger component within the Ariston spares range and is fitted across a number of Clas and Clas HE models.

• Domestic hot water runs hot and cold, or the temperature drifts noticeably during draw-off
• Reduced hot water flow rate at the tap compared with the cold supply
• Water weeping from the exchanger body, its gaskets or the connection points
• Scale or sludge build-up causing restricted flow and poor heat transfer
• Kettling or rumbling noises from the DHW circuit during operation

• Confirm your boiler model and serial number against the compatibility list before ordering, as the same part number can appear across several variants.
• Check the part number on the existing component matches 65104333.
• Inspect the seals and gaskets on removal; a replacement seal kit may be needed to refit the exchanger correctly.
• This part is fitted to a gas appliance; installation must be carried out by a Gas Safe registered engineer.